Trailer light/harness problem

Been dealing with a problem with my trailer wiring harness. I towed my boat on Saturday and all lights trailer lights worked fine. Sunday, went to tow again and the lights wouldn't work except the right/passenger side blinker. Hooked the trailer up to another vehicle and all the lights work , so its not the trailer.

I have taken a multi-meter to the 4 prong plug and only get V on the right blinker connection. Have tracked the the wiring back to this gray plug and the same thing, only get V on the right/passenger blinker. Checked the fuses for blinker, markers and stop and all look okay.



So I am thinking it must be something upstream of thing pig tail. I am not sure where this wire/pig-tail originates from. Any ideas what could be the problem? How to fix it?

Thanks

 

That Gray box might be the trailer light converter box or it will be very close.

Those are known for causing all kinds of light problems .

 

that looks like the Toyota connection for trailer wire harness. Check in the storage compartment under the jump seat, behind driver's seat. That's usually where it lives on Ext cab.

 

Thank you, super helpful. I took a look in there and see a harness that is labeled(right turn signal, stop, left turn signal) that appear to have some fuses, of some type(never seen fuses like this). I am hoping I just have a couple of blown fuse!



I will report back what I find

Thanks again !!

 

Well that was simple! So glad I wasted so much time with the multi-meter trying to find the problem . I didn't even know there was a separate fuse bank/cluster for the trailer wiring. I had 3 blown fuses.



Thanks again!!!!

 

Nice!

it was not very common but common enough in some areas to have the factory trailer wiring harness.

unfortunately I did not get one with the "tow package" but would rather have it myself for this reason. I've gone through 2-3 harnesses just because they fail

 

I wonder what caused all those fuses to blow. I had an issue with mine but I ended up just hacking the plug off and soldering another one on after cleaning the terminals to no avail

 

I'd be willing to bet it's how the trailer is wired.

 

Boat trailer has a fold away tongue, so that it fits in the garage. Wires go through the center of the tongue. Fishing buddy smashed the wires good when he was trying to "help" get the boat ready in the morning. When he smashed the wiring, it shorted and blew the fuses.

When I replaced the bad section of wiring I put a protective sleeve on it to prevent future injury from helpful friends.

 

Hi All, found this thread via searching for causes/solutions to my trailer wiring issues. My ‘03 isn’t equipped with the factory wiring, just the standard parts store tail lights pigtail harness. Been through 3 of these in the last 6 yrs and not sure what do about it. No rhyme or reason to the issues i’ve Been having, plug in trailer no lights work, unplug re-plug hazards work, wiggle jiggle blinkers work but no brake lights, on and on etc. Can’t figure it out.
Is there a way to permanently solve this DIY style? Heard its not an uncommon issue with these trucks.

 

My cure was using 7 pin plugs on all my Toyota vehicles

That way every thing is hard wired once and done.

plus you always have the option for electric brakes

 

Would those bundles of fuses be in the same spot for double cabs? My issue is brake and turn signals work. Marker lights do not. Wondering if I might have the same blown fuse.

 

Just realized this is first gen form. Mines second gen. So it's probably different.

 

Depends on the year, they changed the harness after 2011 but the control box is roughly in the same spot which under the driver side kick panel. As for the fuses everthing is under the hood now.

 

Gotcha. Thanks

 

Had a loose fuse under the hood. 30 amp one. Switched for a new one. Everything works again!!